1. Field of the Invention
The present invention relates to oil well logging and more particularly to an improved method and apparatus for oil and gas well logging wherein a mechanical feeler tool engages each casing collar and causes weight change in a non-electric wireline or slick line that supports the feeler tool, and a chart recorder prints a continuous record that can be compared with existing "as built" well profile information for insuring accurate placement of downhole tools thereafter, using the calibrated slick line.
2. General Background
A "slick line" unit is used in numerous operations performed in an oil and gas well. A "slick line" is basically a non-electric wireline or conductor cable of usually metallic construction. As an example, one of the operations that can be performed using a slick line is the perforation of a joint of well casing. The oil company has an accurate log of the well, defining the exact elevational position of each section of casing, and each joint or collar between sections of casing.
A problem exists when a particular location on a section of casing must be accurately identified a slick line unit does usually have a meter to reflect the length of line that has payed out into the well. However, before perforating a section of casing, as an example, the oil company engineers must be absolutely certain that the slick line unit has positioned the perforating equipment in the exact position desired. Merely reading the meter of the slick line unit to determine how much line has payed out is not good enough. It is an object of the present invention to provide an accurate record in the form of a written log, of various downhole information to be used thereafter in conjunction with slick line operations. The system of the present invention provides an improved method of logging downhole using a slick line to provide slick line units with accuracy of placement in the well bore that was not heretofore available.
An improved process for logging (recording) collars on a non-electric wireline (slick line) uses a recorder with graph paper timed precisely to the movement of the wire on a scale. The scale can be required to match an oil company well log for that well. A device to accurately measure the line load is placed in a position to get an accurate reading. The load measurement device of the present invention is capable of triggering a solenoid upon a fluctuation in weight (either higher or lower) on the line. A feeler tool is provided to hang up in the space between the joints of pipe and is placed on the tool string to be sent down the well. As this tool is lowered or raised at a slow speed the weight of the tool string remains constant until the time when the tool contacts the space between the joints of pipe. This contact causes an increase or decrease in weight depending on the direction of travel of the feeler tool. This weight fluctuation is monitored by a weighing device located at the wellhead area. This increase or decrease will activate a solenoid on the high side or low side depending upon direction of travel. Solenoids mounted on the recorder (which is timed to move at a rate coordinated with the payout of the cable) cause a pin (in a neutral position) to travel right or left depending upon which solenoid is tripped, thus logging (recording) the collars in the well.
Various patent have issued that relate to well logging, and the use of elongated lines in an oil well environment wherein length of line information is desired.
U.S. Pat. No. 3,027,649, entitled "Depth Measuring System", issued to R. W. Sloan, discloses a method and apparatus for accurately and continuously determining the length of an elastic wire or cable under tension and more particularly to the measurement of the true position of a device suspended from an elastic wire or cable whose length varies with change in the tension applied thereto, as when the cable is payed out and taken in to change the position of the device. This device is adapted for use in the logging of a well wherein there is generally recorded some characteristic of earth strata adjacent a well bore as a function of depth. The earth characteristic is obtained by employing an exploration unit or instrument, frequently and generically referred to herein as a logging tool, suspended within a well bore by means of a cable, the length of which may be changed by cable-reeling means located at the surface. The log is generally made while moving the tool uphole or downhole by means of the cable. The cable length is continuously measured or computed to obtain a continuous indication of the tool position within the well bore.
U.S. Pat. No. 3,390,574, entitled "Ton-Mile Marker", issued to W. N. Jones, discloses an apparatus for continuously integrating and indicating on a digital counter the product of tensile load and distance traveled of any flexible line which operates a weighted apparatus such as a traveling block thereby providing an indication of ton-miles.
U.S. Pat. No. 3,538,761, entitled "Ton Mileage Recorder", issued to H. D. Horton et al., discloses a ton mileage recorder for integrating work to which the wire rope and related apparatus of the draw works of a drilling rig is subjected. A travel sensor in the form of a hydraulic pump which is actuated by the traveling wire rope provides power fluid which drives a hydraulic motor. A weight sensor actuates a cam which in turn controls fluid flow from the motor. The motor drives a gear box which in turn is connected to an odometer having indicia thereon in the usual manner. Hence the weight sensor cooperates with the travel sensor by means of the cam which is associated with the pump to thereby integrate the distance which the wire rope travels while being subjected to a finite weight.
U.S. Pat. No. 3,474,539, entitled "Pipe Collar Locator And Method Of Using Same", issued to L. K. Moore, discloses a method and device for locating collars in a pipe, wherein a mechanical device having a catch finger is lowered on a nonelectrical flexible line for engaging the catch finger in a collar upon an upward pull on the flexible line, so that upon an operator observing the increased weight on a weight indicator due to the catch finger engaging in the collar, the length of the flexible line in the pipe can be determined to thus determine the elevation of the collar.
U.S. Pat. No. 3,916,684, entitled "Method And Apparatus For Developing A Surface Well-Drilling Log", issued to Herbert A. Rundell, discloses a method or system for developing a surface drilling log indicative of one or more parameters of the formation being drilled. Measurements include the bit revolutions, the depth of the bit in the hole, the weight on the bit, and a determination of tooth dullness of the bit. The results are correlated to produce a parameter in accordance with the predetermined relationship of the measurements and the determination.
U.S. Pat. No. 4,064,749, entitled "Method And System For Determining Formation Porosity", issued to Robert W. Pittman et al., discloses a method and/or system for measuring formation porosity from drilling response. It involves measuring a number of drilling parameters and includes a determination of tooth dullness as well as determining a reference torque empirically. One of the drilling parameters is the torque applied to the drill string.
U.S. Pat. No. 4,137,762, entitled "Wireline Apparatus For Use In Earth Boreholes", issued to William D. Smith, discloses a wireline that comprises one or more insulated conductors contained within a smooth walled metal sheath; which wireline is used to perform all of the normal wireline operations in an earth borehole and particularly in very deep boreholes; and in which the sheath material of the wireline is a metal having a high yield strength to weight ratio, and the sheath is swaged into intimate contact with the inner insulated conductor or conductors, such that the weight of the inner conductor or conductors and insulation is effectively supported by the sheath.
U.S. Pat. No. 4,787,244, entitled "Well Pipe Or Object Depth Indicator", issued to Raymond F. Mikolajczyk, discloses a movement measuring device which includes circuitry which produces signals functionally related to the amount and direction of movement of a cable or drill line in relation to up and down movement of an object such as pipe and the like in a well bore. A totalizer device is provided with circuitry that is coupled to the movement measuring device to instrumentally display the object depth in the well bore resulting from the signals received from the movement measuring device. A switch is operatively connected to the cable or drill line and a device closes the switch when a predetermined weight or load on the cable or drill line is exceeded to provide power from a power source to the movement measuring device for transmitting the signals therefrom to the totalizer device. The totalizer device continuously displays the total depth of the object in the well bore.